FCR vs. Edelbrock?

BWB63

The power now this would work even better on the Edelbrock because of it's flat slide. It would be nice to send both a bored and a stock Edelbrock. I have Autodesk Inventor 8, and Auto Cad 12. Maybe I can sed you something when I have the carb. off for a while.

porterdog

I've got a QS on the way and plan to tear my bike down for most of the winter to do the suspension (Bruce, did you get my last PM?) so it would be easy for me to make the measurements you need over xmas break.

PM me, and we'll get it taken care of- I think a power now-type blade is a great idea; could do the exit one as well if we want.

BWB63

I know this isn't the suspesnion thread but, here is the answer to your question on the suspesnion. With using the setups from the www.borynack.com/XR650R sight.

Well, it is very diffecult to do both dirt/race and street with the same suspension. The way the shim stacks are setup from the pages of the web sight do have an advantage over the older XR600 way of setting up the suspension. With the thinner fluid, larger port hole in the compression valve of the forks, much more open flow through the compression bypass (compression adjustments) this gives amuch plusher ride over the small ruts, wash board, roots and rocks. The timing is much better through the whoops with the right spring combonation front and back. We have come a long ways in fixing the clicking (short stroke bottoming) as the bike hit multible hits during a 'G' out. Makes a much nicer rider over pot holes, cracks and bumps on the street but, setup for dirt does not help with true SM street riding. The problem is in the flickablility of the bike with this plush suspension and the excessive dive you will have. As you flick the bike over the bike will want to over compress, as it will when you dive into the twisties. The up side is there is so much room to adjust the compression on this setup you have to room to adjust stiffer to stop this dive. When it comes to stopping the suspension from opening up to early as pass through the apex of turn or as you transfer/flick the bike the rebound control is awesome with the shim setups but, you have little room to stiffen up the rebound without stacking going back to the dirt. I see no reason that the rebound would have to be changed and if it did it would be only one click from 11 clicks out to 10, on both the forks and shock. The fork compression could need to be brought from 16 clicks out to as stiff as 8~10 maybe stiffer if you are really pushing it and from 16 clicks out on the shock to somewhere around 10 clicks out on the shock. Got to fly, I am at work and didn't proof read this (like I ever do), hope it reads right.

Hi Bruce! Are you still doing damper mods? I'm going to tear my pig down this winter for some other stuff and well... you've got an awfully good rep with this bike

TIA,Robert

I do damper mod's as well as suspension mod's I know real funny guy right? What do you have in mind? What is your time line, weight, how much air do you wish to get with your BRP? You can use some of the video's off my web sight to get an idea of what you might be after. What did you want to pay for the suspension work? What springs are you going to get? I am getting away from doing suspensions for those I have not ridden with. The reason is I don't like to just spit out generic shim stacks but, something that will make the rider better then he ever thought it could be. I am happy with just doing the suspensions for the district #37, BITD and SCORE guys. I have some time the next two weeks. http://borynack.com/XR650R/

Hey, thanks for getting back to me.

LOL, yes, funny. As an engineer I can't bring myself to say 'shock absorber' in this context. I live in Michigan, it's cold and icy, and I have a broken arm.... You could describe my timeline as 'relaxed' . As in, I should have it back together by mid-April.

I weigh 185 in my birthday suit. Figure 210 or so with gear.

Air... see below.

Fully expect to pay; no issues. I could get it done locally by guys that know the area but are weak on this bike, and I'd rather support a guy that does it 'cause he's into it than somebody who just wants to get me in and out.

We've never ridden together, unfortunately, and as I live way away, probably that will always be the case unless I can engineer a work trip to your zone.

My XRR is a bike-of-all trades. SM trim during the week, so I like firm control on our craaaapy pavement. On the weekends I'll swap back to dirt tires/wheels and ride Michigan's famous sandy whoopy rocky singletrack and/or fast dirt forest roads. I'd really like to have something that has enough adjustability that I can have good performance on both, if possible. It's unlikely I'll ever do any serious race-type jumping, though trips to the dunes are possible. Big air is lower on my list of priorities, but dual sport riding with some gear is up there...

Some suggest aircells as one good way to get a dirt/street setup; I may be willing to give that a go in the future, but I have to revise my control setup this winter and am considering a pumper carb so the aircells will have to wait for financial reasons.

jesusgatos

Thanks, that would be great. I just called Scary Fast Racing (comany that make the Power Now system), and asked whether they would be willing to just make a part for this application. They're going to look into it and get back to us, via. me.

I had the older TM38 on my XR628R race bike back in the day but, I really think it could have taken the TM40 just fine without being wet. I have a write up with dyno charts of the TM40 vrs the Edelbrock and bored Edelbrock. In the end the Edelbrock had a strange dip in the low rpm's but, bored put out more power in the upper RPM. You don't realy feel the dip but, the dyno says it is there and that is after we worked for hours doing our best to get rid of the dip. It was way, way worse till we adjusted the pump way rich. Barnum thought that with more load on the engine is what makes it not bad enough to feel. The Mikuni was way smoother from bottom to top. That is dew to the fact that it is way more tunable. We did favor the Edelbrock (we were using their dyno and there tuners for the prodject) so, the Mikuni didn't get any time at being tuned to it's best. The jets were not change for any of the runs and even when the bike went to 680cc the Mikuni was left with the same jets as was used when test on the 650cc bike. This was do true with the Edelbrock, everything was messed with till we just ran out of time....well, the bike seized.

Thumpage

I had the older TM38 on my XR628R race bike back in the day but, I really think it could have taken the TM40 just fine without being wet. I have a write up with dyno charts of the TM40 vrs the Edelbrock and bored Edelbrock. In the end the Edelbrock had a strange dip in the low rpm's but, bored put out more power in the upper RPM. You don't realy feel the dip but, the dyno says it is there and that is after we worked for hours doing our best to get rid of the dip. It was way, way worse till we adjusted the pump way rich. Barnum thought that with more load on the engine is what makes it not bad enough to feel. The Mikuni was way smoother from bottom to top. That is dew to the fact that it is way more tunable. We did favor the Edelbrock (we were using their dyno and there tuners for the prodject) so, the Mikuni didn't get any time at being tuned to it's best. The jets were not change for any of the runs and even when the bike went to 680cc the Mikuni was left with the same jets as was used when test on the 650cc bike. This was do true with the Edelbrock, everything was messed with till we just ran out of time....well, the bike seized.

I am thinking there is an alternative route or additional route to take for getting a more consistant fuel metering curve for the Edlebrock and this is using a Dial-A-Jet from Thunder Products; http://www.thunderpr.../dial_a_jet.htm The dial-a-jet should act as an extra fuel circuit throughout the whole jetting range. This could be the ticket to making the Edelbrock completely tunable from bottom to top. I had been eyeballing these way back when, when I was considering trying one on a stock carb to get it to respond right off the bottom without the usual stumble. As billed, the dial-a-jet should be able to fill in any lean spots or weak fuel metering transitions with the Edelbrock. I can only guess that the dip shown on the dyno performance of the Edelbrock possibly came from after the pump shot was exhausted and the fuel metering from the needle was just barely catching up at that point. With the dial-a-jet the pump shot could be backed off to a more normal setting or possibly even less of a shot to begin with and all the while the super light emulsified fuel metered from the dial-a-jet will help quicken, fill in and smooth the fuel delivery. As for the Power Now type venturi dividers, there is another company that makes a version that fits in after the slide such as the Power Now 'Plus'. Their product is called the Power Pack; http://www.slp.cc/ca...cfm?catalogID=1

Their system uses two plates. They make them for various machines and carbs. I know that this is a little different from the version that installs before the slide but it is supposed to work on the premis of reducing the eddy that occurs after the slide and helps in speeding up and smoothing the airflow into the ports. Now if we could find out if they make a version that will fit the Edelbrocks venturi size/shape, then we could have something good with this also. It should be all about finding a carb for whatever machine that has the same venturi size. 39mm for the stock Edelbrocks might work? 40mm,41mm for use in the bored out Edelbrocks? One of their versions may or may not work depending on whether they will fit correctly in the Edelbrocks slightly oval, (or less oval, bored out) venturi profile. They have to fit snug. Refer to the Adobe fitment instruction file on any one of the application pages, ie., Power Pack for Honda bikes page. With either a dial-a-jet or venturi plate/s and especially both working in unison, maybe a whole new performance level can be obtained from the Edelbrock.

BWB63

The dial a jet might help, if you do with a smaller number needle. The Edelbrock has a eliptical venturi, intill it is bored out. Even then it isn't round. Bored Edelbrock mesures just about 41mm horizontally and 42mm verticaly. There is a big change if how the edelbrock performs once there is load on the engine and not just spinning a drum. The whole low end curcuit is more then just a jet likr the dial a jet. There is an air jet and for the emulsion holes to atomize the fuel. Got to go to work.

jesusgatos

Search TT for 'powernow plus'. I'm pretty sure that I've seen dyno tests posted somewhere on this forum (maybe in the Yamaha section?) that show the engine LOST power after installing the powernow plus (compared to just the power now).

donnyh

This is a great thread, thanks guys, I have a new EB ready to be installed on my 650L.

I have been scared to click on this thread only to find out I bought the wrong carb, but after reading all this input, I think I got the right carb for my situation.

The Edelbrock doesn't flood. To me, that is HUGE, on an electric start bike with no kick start, not flooding may save my battery, and save me from hiking out sans thumper.

The adjustability: I live over 4k in elevation, my local trails range up to 6k, my favorite destination from here are the Uintahs, trails up to 10k, and I work 4 months of the year at sea level in SoCal, and will use the 650 to commute.

I need the carb that deals with elevation changes the best, with easier tuning, of the available choices, I think the EB is still the right carb for me.

weskc35k

The dip off the bottom is not much to do with the carb it's more and more prevalent the higher the state of tune,as you're pushing the power up the range.
This is why i still run the stock headers at the moment.
I have ordered a set of wrap around headers from Dave at MRD,but i will change a few things so i don't lose too much from the bottom.
I may advance the cam a bit,or go with an XR400 CDI or go to a higher comp piston or all these things or none depends on how i want the bike to perform.

HawkGT

Search TT for 'powernow plus'. I'm pretty sure that I've seen dyno tests posted somewhere on this forum (maybe in the Yamaha section?) that show the engine LOST power after installing the powernow plus (compared to just the power now).

I've posted some dyno runs showing that (general section, I think). Not sure if those are the ones you saw. In the tests I've seen, an FCR at WOT looses a significant amount at high RPM. Carbs that already have an obstruction in the venturi (like a butterfly valve in the examples I've seen or possibly a choke plate would be similar) aren't effected as much.

The testing I've seen seems to indicate those wings help slightly at lower rpm and at part throttle openings (regardless of RPM) but harm WOT high rpm running. And that makes sense to me. At WOT any kind of wing in the venturi is just an obstruction.

BWB63

I would agrea with HawkGT on this thought. I think the main issue here is that the Edelbrock is trying to do to much for trying to do everything with just a main jet and the needle. This plate/wing thing just might be enough to stop the eddie at the slide to help the bottom end. If this wouldn't hurt the WOT to much it maybe a good enough trade to get a smoother Edelbrock. The Dial-a-jet idea is something to think about also but, this would take a lot of messing around to get the right needle number and that needle number at the right number of clicks out from full rich. I think this is becoming more of a think tank thread that has the possibility of coming up with something that may improve an already good thing.

I think that the power now and dial-a-jet were always things that had limited benifit if any for a well tuned pumper carb., like the FCR of Mikuni but, as for the Edelbrock having a limited range of adjustability for each part of the slide movement, these little things may make a bigger difference. I have never seen the need for the dial-a-jet on anything but a CV carburetor, till it was brought up here. It would take a lot of testing and then dyno time with the bike being all the same, tested till the Edelbrock gave it's best performance and then with what ever you are going to add and then test it till you get that setup right. Like I mentioned before even doing the best I could, time and trying to keep everything in perspective the Mikuni TM40 didn't get as much time/attention/tuning when on the dyno as did the Edelbrock. Even with that said, the Mikuni gave much smoother power and was much more consistant even when we change something on the bike then was the Edelbrock. We have the full attention of the whole Edelbrock R&D shop and every tweek was done to make this Edelbrock the best it could be. The Edelbrock did not make as much power on a XR650R with free-flowing header/muffler as the TM40 Mikuni no matter what was done to it but, once the Edelbrock was bored it did give more horsepower and once we went 680cc with cam, over-sized intake valves, 11:1 weisco The Edelbrock was tweeked even more, with the jet changed (no big difference) and they messed with the needle flow and other stuff. Three different stations with different test stuff. Back and forth till they got it to do the best on the dyno they could the Mikuni TM40 was left with the same jetting it had when the bike came through the door and that was the same jetting that was used when it was a 650cc motor and now was being used on the 680cc motor. Would everyone think that if the Mikuni TM40 would have got that attention it would have turned out a little better numbers on the dyno? Another thing that is over looked by most is that it isn't all about peak housepower but, where in the rpm curve that horsepower is being compared. You can have more peak horsepower but, at other parts of the RPM curve the other carb. could be better. [COLOR="Blue"]What about machining the venturi for the plate? I don't like the idea of the pressed fit anyways and making the venturi smaller is counter produtive. A groove on both sides with holes for tabs on the plate to fit into????[/COLOR]

Krannie McKranface

I would agrea with HawkGT on this thought. I think the main issue here is that the Edelbrock is trying to do to much for trying to do everything with just a main jet and the needle. This plate/wing thing just might be enough to stop the eddie at the slide to help the bottom end. If this wouldn't hurt the WOT to much it maybe a good enough trade to get a smoother Edelbrock. The Dial-a-jet idea is something to think about also but, this would take a lot of messing around to get the right needle number and that needle number at the right number of clicks out from full rich. I think this is becoming more of a think tank thread that has the possibility of coming up with something that may improve an already good thing.

I think that the power now and dial-a-jet were always things that had limited benifit if any for a well tuned pumper carb., like the FCR of Mikuni but, as for the Edelbrock having a limited range of adjustability for each part of the slide movement, these little things may make a bigger difference. I have never seen the need for the dial-a-jet on anything but a CV carburetor, till it was brought up here. It would take a lot of testing and then dyno time with the bike being all the same, tested till the Edelbrock gave it's best performance and then with what ever you are going to add and then test it till you get that setup right. Like I mentioned before even doing the best I could, time and trying to keep everything in perspective the Mikuni TM40 didn't get as much time/attention/tuning when on the dyno as did the Edelbrock. Even with that said, the Mikuni gave much smoother power and was much more consistant even when we change something on the bike then was the Edelbrock. We have the full attention of the whole Edelbrock R&D shop and every tweek was done to make this Edelbrock the best it could be. The Edelbrock did not make as much power on a XR650R with free-flowing header/muffler as the TM40 Mikuni no matter what was done to it but, once the Edelbrock was bored it did give more horsepower and once we went 680cc with cam, over-sized intake valves, 11:1 weisco The Edelbrock was tweeked even more, with the jet changed (no big difference) and they messed with the needle flow and other stuff. Three different stations with different test stuff. Back and forth till they got it to do the best on the dyno they could the Mikuni TM40 was left with the same jetting it had when the bike came through the door and that was the same jetting that was used when it was a 650cc motor and now was being used on the 680cc motor. Would everyone think that if the Mikuni TM40 would have got that attention it would have turned out a little better numbers on the dyno? Another thing that is over looked by most is that it isn't all about peak housepower but, where in the rpm curve that horsepower is being compared. You can have more peak horsepower but, at other parts of the RPM curve the other carb. could be better. [COLOR="Blue"]What about machining the venturi for the plate? I don't like the idea of the pressed fit anyways and making the venturi smaller is counter produtive. A groove on both sides with holes for tabs on the plate to fit into????[/COLOR]

You keep refering to a 'free-flowing header' but don't give a description/brand/model. I have seen after market headers that mimick the exhaust port size all the way to the mid pipe, some that taper up to, some that junction up to (like stock), and some that are massive. I would think they ALL are free-flow, but ALL have vastly different characteristics. Has anyone compared them (and I don't mean on a dyno, which means nothing to me personally).

BWB63

You keep refering to a 'free-flowing header' but don't give a description/brand/model. I have seen after market headers that mimick the exhaust port size all the way to the mid pipe, some that taper up to, some that junction up to (like stock), and some that are massive. I would think they ALL are free-flow, but ALL have vastly different characteristics. Has anyone compared them (and I don't mean on a dyno, which means nothing to me personally).

The stock header is not a freeflowing header. It is very restricktive just out of the head. Yes, I have tested many different headers on the XR650R. Free flowing header would be a header with I.D. of at least 1.125" tubes from the head to the colector. This is most of the headers, XR's Only, FMF, pro curcuit. The major freeflowing header would be Barnum's, Moriwaki or any others that have 1.25" tubes to the collector 1.75" mid section and 2" I.D. pipe to and trough the muffler. There is tons of talk about the different headers for the XR650R and what there benifit is. Do a search and pick one that is about a year old.

Krannie McKranface

The stock header is not a freeflowing header. It is very restricktive just out of the head. Yes, I have tested many different headers on the XR650R. Free flowing header would be a header with I.D. of at least 1.125" tubes from the head to the colector. This is most of the headers, XR's Only, FMF, pro curcuit. The major freeflowing header would be Barnum's, Moriwaki or any others that have 1.25" tubes to the collector 1.75" mid section and 2" I.D. pipe to and trough the muffler. There is tons of talk about the different headers for the XR650R and what there benifit is. Do a search and pick one that is about a year old.